1. Field of the Invention
The present invention generally relates to a portable terminal system, an option apparatus for a portable terminal unit, and a method for connecting the portable terminal unit and the option apparatus for portable terminal unit. More specifically, the present invention is directed to such a technique capable of firmly connecting the portable terminal unit and the option apparatus in a simple manner even when this option apparatus owns a different physical interface from the physical interface of the portable terminal unit.
2. Description of the Related Art
Very recently, portable terminal units such as portable telephones and mobile computers have been developed. Among these portable terminal units, for instance, various adapter apparatuses are optionally connectable with portable telephones in order to newly add functions and/or so as to improve usability. This adapter apparatus will be referred to as an "option apparatus" in this specification. Also, a function realized by connecting such an "option apparatus" to a portable terminal unit will be referred to as an "option function" in this specification. For example, a hands-free adapter and a data adapter are involved in an option apparatus for a portable telephone. Such an "option apparatus" is commercially available as optional equipment for a portable telephone.
Conventionally, a wire line transfer path is employed so as to connect an option apparatus to a portable terminal unit. For instance, as indicated in FIG. 1, an option apparatus 41 for a portable telephone is connected to a portable telephone 51 by employing a cable 61. In this case, a connector 46b provided at one end of this cable 61 is connected to the connector 46a provided with the option apparatus 41 for the portable telephone, and further another connector 60b provided on the other end of the cable 61 is connected to another connector 60a provided on the portable telephone 51. As a result, the option apparatus 41 for the portable telephone is electrically connected to the portable telephone 51 so as to communicate with each other.
The above-explained conventional method for connecting the portable terminal unit to the option apparatus with employment of such a connector owns the following problem. That is, since the connector must be physically fitted between them under tight condition, the connecting work of the option apparatus cannot be smoothly performed. Also, since this connecting work must be carried out while fixing both the portable telephone and the option apparatus, the difficult connecting work is necessarily required.
Also, the conventional connection methods for connecting the portable terminal units to the option apparatuses are different from each other, depending upon the manufactures of these products. On the other hand, portable terminal units are gradually made compact and are operable under low consumption power in response to market needs. Accordingly, the shapes of these portable terminal units and also the physical interfaces provided between the portable terminal units and the option apparatuses are gradually changed. To the contrary, since compact-requirements and low-operable-consumption-power requirements with respect to the option apparatuses are not so strong, as compared with those for the portable terminal units, the physical interfaces and shapes of these option apparatuses still remain, namely are not changed. As a consequence, there is another problem that when one portable terminal is replaced by a new one, the originally used option apparatus can be no longer used with, of course, a newly purchased portable terminal unit marketed by a different manufacturer, but also even a newly purchased portable terminal unit marketed by the same manufacturer.
Under such a circumstance, another technique capable of connecting a portable terminal unit to an option apparatus by employing other means than the cable would be expected. As one typical connecting technique, for example, Japanese Laid-open Patent Disclosure JP-A-Heisei 3-162021 opened in 1991 discloses such a portable telephone arranged by a main body unit and a telephone receiver unit detachably connected with this main body unit. In this conventional portable telephone, the speech signal received by the main body unit is converted into the infrared signal, and the telephone receiver unit demodulates the received infrared signal to thereby produce the speech signal. Then, the speaker produces speech, or voice in response to this demodulated speech signal. As a result, the telephone conversation can be made in the case that the main body unit is coupled to the telephone receiver unit, and further even when the main body unit is separated from the telephone receiver unit. Also, Japanese Laid-open Patent Disclosure JP-A Heisei 3-162024 discloses another portable telephone improved from the above-explained portable telephone opened in Japanese Laid-open Patent Disclosure JP-A-Heisei 3-162021. This improved portable telephone is arranged in such a manner that the infrared LED is provided on the surface of the main body unit, which is coupled to the telephone receiver unit, and the infrared LED is provided on another surface thereof located opposite to the first-mentioned surface. As a result, even when the main body unit is positioned in the reverse direction, the telephone conversation can be established between the main body unit and the telephone receiver unit.
However, in these conventional portable telephones described in Japanese Laid-open Patent Disclosure JP-A-Heisei 3-162021 and JP-A-Heisei 3-162024, the telephone communications are established between the main body units and the telephone receiver units, which constitute an portion of the respective portable telephones, but no telephone communications are carried out between the portable telephone and the option apparatus. Moreover, these conventional portable telephones introduce such a unidirectional communication technique that the speech signal received by the main body unit is transmitted to the telephone receiver unit. As a consequence, this unidirectional communication technique is not suitably applied to such a connection technique for electrically connecting the portable terminal unit to the option apparatus.
On the other hand, Japanese Laid-open Patent Disclosure JP-A-Heisei 6-291714 opened in 1994 describes the radio selective paging receiver. In this conventional radio selective paging receiver, when a telephone call is made, both the signal used to initiate the mobile telephone and the signal used to issue the dialing call by employing the telephone number are transmitted to the mobile telephone by using the infrared radiation. However, the counter appliance to which this conventional radio selective paging receiver transmits the infrared signals is not an option apparatus of this paging receiver, but is another mobile telephone, for instance, the portable telephone, the automobile telephone, and the cordless telephone. Moreover, this conventional radio selective paging receiver can employ only the unidirectional communication system similar to the aforementioned conventional portable telephones described in Japanese Laid-open Patent Disclosure JP-A-Heisei 3-162021 and JP-A-Heisei 3-162024.
On the other hand, Japanese Laid-open Utility Model Disclosure JU-A-Heisei 6-31241 opened in 1994 discloses the hands-free type automobile portable telephone. This automobile portable telephone is connected to the external speaker by employing the infrared communication means. However, this conventional automobile portable telephone merely introduces the unidirectional communication technique.
Moreover, Japanese Laid-open Patent Disclosure JP-A-Heisei 8-293830 opened in 1996 discloses such a portable telephone for transmitting/receiving the data between this portable telephone and the display adapter employing the infrared emitting element and the infrared receiving element. This data is also transmitted/received between the public network and this portable telephone. However, the display adapter does not own the radio transmitting/receiving function capable of directly communicating with the public network. As a consequence, in the case that the data is transmitted/received via the public network between this portable telephone and other apparatus, another portable telephone having the radio transmitting/receiving function is necessarily required. Therefore, the utilization of this conventional display adapter is limited to a specific field.